The present invention relates to light projectors of the kind comprising a condenser system and a shutter in front of a connector socket arranged to receive the plug of an optical fiber cable insertible thereinto, the proximal end of which plug adjacent the projector is reduced in diameter and surrounded by a heat conductor.
Optical fibers are joined together into a bundle and indissolubly coupled by means of a glass adhesive, for connection to a light projector. The fibers immobilized in the plug in this manner terminate at the proximal end facing towards the light projector with the end face of the diametrically reduced plug section. If the light beam of a light projector is then beamed into the end face of an optical fiber cable of this kind, this leads to partially substantial heating of the plug as a function of the output of the light projector. Since optical fiber cables are utilized with a thick as well as thin fiber bundle cross-section, it is necessary to perform the focussing of the light beam by means of a condenser system on comparatively narrow fiber bundle cross-sections to be able to emit a maximum light output. Since light conducting cables having a comparatively large fiber bundle cross-section undergo a very rapid temperature rise due to the low radially outwardly directed heat dissipation of the glass fiber, particularly in the area of the end light incidence, this results in a complementary rise in temperature caused by ultraviolet radiation of the projector light, because of the high heat absorption of the adhesive or bonder. The glass bonder present between the glass fibers of the plug is thereby liquified and issues from the individual fiber gaps with subsequent burning and blackening of the fibers, which leads to another constant temperature rise with final destruction of the plug.
In order that the heating of the reduced diameter proximal end of the plug caused by the light of the projector may be reduced, it has already been proposed to insert the proximal diametrically reduced plug section into a bore of an aluminium block including external cooling fins, in which the light source is present. The light is beamed into the end side of the plug via the bore as described in German Offenlegungschrift No. 19 28 360. This measure has not proven entirely satisfactory in assuring either an adequate heat dissipation at the plug, or prevention of eye injuries by the high-intensity light emerging from the socket. Further, the application of cooling elements of this nature remains restricted to lamps of the proposed kind.
It is thus an object of the invention to minimize or prevent heat accumulation in the area of the light ingress into the plug and, in the case of light projectors of very high light output and comprising a connector socket for the plug of an optical fiber cable of optional cross-section. A second object consists in that a light emission by the projector should occur only when the cable plug is wholly inserted and secured in the connector socket, to prevent eye injuries during operation thereby.